MANUFACTURE  OF  AMMONIA,  ETC. 
225 
ON  THE  MANUFACTURE  OF  AMMONIA  AND  AMMONIACAL  SALTS. 
(Concluded  from  page  139.) 
A  great  variety  of  processes  have  been  patented  within  the 
last  few  years  by  Mr.  Laming  and  Mr.  Hills,  having  for  their 
object  the  purification  of  coal  gas  and  the  obtaining  of  ammonia 
and  ammoniacal  salts.  In  his  patent  of  November  4,  1847,  Mr. 
Laming  claims  the  use  of  the  undermentioned  salts  for  the  above 
named  purposes,  the  solution  of  which  is  absorbed  into  sawdust, 
or  other  porous  material,  and  placed  in  the  purifying  vessel  of 
the  gas-works — viz.,  chloride  of  calcium,  the  muriates  and  sul- 
phates of  manganese,  iron,  and  zinc;  the  carbonates  of  manganese, 
iron,  zinc  and  lead.  The  oxides  of  manganese,  iron,  zinc,  or 
lead,  may  also  be  added  to  any  of  the  above  materials.  The 
ammonia  or  ammoniacal  salts  contained  in  the  spent  purifying 
materials  may  be  removed  by  heat  or  washing. 
The  specification  of  the  same  patent  contains  an  account  of 
certain  modes  of  treating  the  ammoniacal  liquor  of  gas-works,  so 
as  to  obtain  from  it  the  sulphate  of  lead,  a  solution  of  sulphate 
of  ammonia,  and  either  an  oxide  or  carbonate  of  lead,  of  sufficient 
purity  to  serve  as,  or  be  converted  into,  white  lead. 
Mr.  Laming  converts  the  hydrosulphate  of  ammonia  contained 
in  gas-liquors  into  carbonate  of  ammonia  by  the  following  pro- 
cess : — A  mixture  of  deutoxide  of  copper  and  charcoal,  or  other 
form  of  carbon  in  fine  powder,  in  the  proportion  of  twelve  parts 
by  weight  of  the  former  to  one  of  the  latter,  is  introduced  into  a 
retort  made  red-hot  and  furnished  with  an  eduction-pipe,  which 
passes  through  cold  water,  and  finally  enters  into  the  gas-liquor. 
The  formation  of  carbonic  acid  gas  soon  takes  place  by  the  union 
of  the  carbon  with  the  oxygen  of  the  metal,  and  this  gas  com- 
bining with  the  base  of  the  hydrosulphate  of  ammonia  contained 
in  the  gas-liquor,  converts  it  into  carbonate,  with  liberation  of 
hydrosulphuric  acid.  When  the  carbonic  acid  gas  ceases  to  come 
away,  nearly  all  the  carbon  will  have  disappeared  from  the  retort, 
and  the  copper  which  it  contains  become  reduced  to  the  metallic 
state.  The  charge  is  then  drawn  and  left  to  cool,  while  a  second 
charge  of  similar  materials  is  being  worked  off,  during  which 
time  the  copper  re-absorbs  oxygen  from  the  air,  and  becomes 
again  deutoxide  of  copper,  which  may  then  be  used  anew  with 
fresh  carbon. 
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